1. Field of the Invention. This invention relates to flashlight assemblies and, more particularly, to a shock absorbent flashlight assembly.
2. Prior Art. One type of flashlight assembly includes a metal cylindrical battery housing which contains batteries. External threads on one end of the metal cylindrical battery housing are threaded into internal threads at one end of a cylindrical reflector subassembly. A bulb is mounted to a bulb mounting subassembly which axially moves within the reflector subassembly along the axis of the reflector subassembly. A spring mounted in the reflector subassembly biases the bulb mounting subassembly away from the reflector subassembly so that the bulb mounting subassembly contacts the one end of the metal cylindrical battery housing. The axial position of the bulb mounting subassembly within the reflector subassembly is adjusted by screwing the external threads on the one end of the metal cylindrical battery housing into and out of corresponding internal threads in the cylindrical reflector subassembly.
The bulb is mounted to the bulb mounting subassembly by inserting two lead-pins of the bulb into sockets which are pressed fit into the bulb mounting subassembly to provide a voltage from the batteries to the bulb. The reflector subassembly has an axial hole through which the bulb extends. The axial position of the bulb along the axis of the reflector is adjusted by screwing the external threads on the one end of the metal cylindrical battery housing into and out of corresponding internal threads in the cylindrical reflector subassembly. Adjustment of the axial position of the bulb along the axis of the reflector allows adjustment of the focus of the beam of light from the flashlight, as needed.
A severe environment for flashlight assembly such as described above is when it is mounted to a weapon such as a pistol or rifle and is subjected to severe shock and vibration caused primarily by recoil inertial forces produced by rapidly expanding gases generated when a bullet or projectile is fired from the weapon. In the case of an automatic pistol or rifle, another source of shock and vibration is the abrupt movement of the automatic slide-mechanism for ejecting a spent shell or cartridge and reloading an unfired shell or cartridge. This shock and vibration courses both axial and radial displacement of the bulb from the flashlight when a cylindrical coordinate system is used.
The invention is useful for other lighting applications where the flashlight or light source is subject to being dropped or subject to other shock or mechanical vibrations that may break the light bulb or filament.
It has been found that the usual pin-and-socket arrangements described above for mounting the bulb in a flashlight assembly mounted, for example, to a weapon have resulted in failure of the flashlight bulb caused by the glass envelope of the bulb striking the sides of the axial hole in the reflector. The forces caused, for example, by firing the weapon also can misalign the bulb in the sockets so that it is not centered along the axis of the flashlight resulting in an uneven plume of light.
Consequently, a need exists for a technique to reduce shock or vibration induced failures flashlight assembly. A need also exists for keeping a bulb properly aligned within a flashlight assembly.